Showing posts with label drug resistant. Show all posts
Showing posts with label drug resistant. Show all posts

Monday, September 28, 2015

Scientists identify new agent to combat tuberculosis

Click to see the large picture

New hope in the fight against tuberculosis

Above pic: The protein forms a homodimeric ring (shown as blue cartoon & surface representation). Each polypetide chain binds one molecule of griselimycin (red). The optimized compound cyclohexylgriselimycin contains an additional cyclohexane moiety (yellow, shown only for the ligand in the foreground).

According to figures of the World Health Organization, some 8.7 million people contracted tuberculosis in 2012 and this disease is fatal for approximately 1.3 million people throughout the world each year. One of the main problems is that the tuberculosis pathogens have become resistant to the antibiotics used to fight them. Scientists from the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) in Saarbrücken, the Helmholtz Centre for Infection Research (HZI) in Braunschweig and the German Center for Infection Research (DZIF) joined forces with scientists from Sanofi, a global health care company, and identified a new agent, which might potentially remedy these problems. The scientists just described this agent and its unique mechanism of action in the highly renowned scientific journal Science.

Mycobacterium tuberculosis is the main cause of tuberculosis. The treatment for drug-susceptible tuberculosis consists of the daily administration of multiple drugs for a minimum of six months. Lack of adherence to this regimen can result in treatment failure and the emergence of drug resistance. "Complexity and duration of the treatment are true issues and the main reasons for the development of resistant pathogens," says Prof Rolf Müller, who is the Executive Director and head of the Microbial Natural Substances department of the HIPS, an institution jointly sponsored by the HZI and Saarland University.

Consequently, there is an urgent need for new medications and therapeutic approaches to both fight the resistant pathogens, as well as to shorten the duration for the treatment of drug-susceptible organisms. Based on earlier reports, Müller, in collaboration with Prof Jacques Grosset from the Johns Hopkins University School of Medicine in Baltimore, and his colleagues from the HZI and Sanofi scientists, initially focused on the natural substance called griselimycin. The potential of this natural substance, was discovered in the 1960s. However, due to the success of other tuberculosis medications and its low efficacy in an infection model, the substance was not developed any further at the time.

"We resumed the work on this agent and optimised it such that it shows excellent activity in the infection model - even against multi-resistant tuberculosis pathogens," says Müller. In the course of their work, the scientists discovered that cyclohexylgriselimycin, a variant of griselimycin, is particularly effective against Mycobacterium tuberculosis, both in cells and in the animal model. Importantly, cyclohexylgriselimycin was effective when administered orally, which is key in tuberculosis treatment, non-orally available drugs are extremely burdensome to administer daily during the many months of treatment. Moreover, combining this substance with current TB antibiotics increases the efficacy compared to the antibiotic cocktail that is usually administered.

Wednesday, April 10, 2013

Pain reliever shows anti-viral activity against flu

In continuation of my update on naproxen

New influenza vaccines must be developed annually, because the surface proteins they target mutate rapidly, the way cars used to get a whole new look every year. The researchers, led by Anny Slama-Schwok of the Institut National de la Recherche Agronomique, Jouy en Josas, France, found a much more stable, reliable target for anti-influenza activity. The so-called ribonucleoprotein complexes are necessary for replication, and the researchers realized they could target the nucleoprotein, preventing assembly of the complexes. Because of its vital function, the nucleoprotein is highly conserved, making it a good potential target for antiviral drugs.

The nucleoprotein's three dimensional structure, solved in 2006, provided the basis for searching for new drugs that could interfere with its action. The researchers did a virtual screening within the Sigma-Aldrich online catalog of biochemicals. That screening identified Naproxen, better known as the over-the-counter pain reliever Aleve, and as expected, it bound to the nucleoprotein, and impeded RNA binding, says Slama-Schwok. In further testing, it reduced the viral load in cells infected with H1N1 and H3N2 influenza A virus, and in mice it demonstrated a therapeutic index against influenza A that was superior to that of any other anti-inflammatory drug.

Specifically, naproxen blocks the RNA binding groove of the nucleoprotein, preventing formation of the ribonucleoprotein complex, thus taking the vital nucleoproteins out of circulation. The researchers write that naproxen is a lead compound for drug development that could be improved by tweaking the molecule to boost its ability to bind to nucleoprotein.

As an already approved drug, naproxen could become a treatment against influenza relatively quickly, the researchers write. Its status as a non-steroidal anti-inflammatory drug (NSAID), which inhibits the COX-2 pathway, as well as an antiviral would boost its efficacy.
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Thursday, January 10, 2013

Friday, September 9, 2011

Redesigned Vancomycin As Potent Antimicrobial Activity Against Vancomycin-Resistant Bacteria...

In continuation of my update on vancomycin....
A team of scientists from The Scripps Research Institute has successfully reengineered an important antibiotic (Vancomycin)  to kill the   deadliest antibiotic-resistant bacteria. The researchers claim that compound could one day be used clinically to treat patients with life-threatening and highly resistant bacterial infections. The compound synthesized is  an  analogue of the well-known commercial antibiotic vancomycin.

Vancomycin normally works by grabbing hold of and sequestering the bacterial cell-wall making machinery, a peptidoglycan (carbohydrate and peptide containing molecule). Only Gram-positive bacteria have a cell wall, which is a membrane on the cell's outer surface. Unfortunately, bacteria have found a way to alter the peptidoglycan in such a way that the antibiotic can no longer grab hold. Researchers claim that,  the new vancomycin analogue can grab hold of the mutant peptidoglycan, and again prevent the bacteria from making the cell wall and killing the resistant bacteria. But what is so remarkable about the design is that the redesigned antibiotic maintains its ability to bind the wild type peptidoglycan as well.

New compound has an amidine (an iminium, RC=NH+ linked to a nitrogen, N) instead of an amide at a key position buried in the interior of the natural product. I appreciate the idea and the simplicity in achieving the target functional group.

Researchers add that, although it is still at its early stages and there is much work ahead.In my opinion it is a good beginning...

Tuesday, May 17, 2011

Novel two-drug combination cures young patient with extensively drug-resistant tuberculosis

The combination of meropenem (above structure)  with clavulanate (right structure-potassium salt)  has high antimycobacterial activity in vitro against extensively drug-resistant Mycobacterium tuberculosis strains. Researchers report the successful use of this combination in association with linezolid (below structure)  in the management of an advanced extensively drug-resistant tuberculosis disease with complex second-line drug resistance in a 14-year-old teenager.